The ever-changing demands of global commerce, coupled with the almost unlimited capabilities of state-of-the-art imaging systems, has resulted in a need for a wide variety of document types and formats. The days of "letter or legal" have gone the way of carbon paper and mimeographs. Imaging systems are capable of handling a variety of standard sizes, such as letter, legal, A4, and A5-ISO, as well as custom sheet sizes.
Rather than require system users to have on hand a different sheet tray for each sheet size, it is known to provide cassette trays having the ability to handle a relatively wide range of sizes. Such trays are sometimes provided with sliding rear adjustable "backstops" which may accommodate different sheet lengths, and/or side slide-plates adjustable to communicate sheet size information to the printer central control system.
Two approaches to sheet size adjustability are exemplified by the optional 500-sheet tray and the standard 250-sheet tray associated with the Hewlett-Packard LaserJet 4000T printer. The optional 500-sheet tray supports standard sheet sizes, as well as custom sizes. The sheet size in the tray is communicated to the printer by contact with combinations of three levers on the side of the tray. The levers are capable of selective contact with switches on the interior of the sheet infeed housing when the tray is inserted into the printer. Each sheet size is associated with a unique set of lever positions. The levers are moved in and out by the slide-plate, which is mounted on the side of the tray. The slide-plate is provided with a plurality of holes corresponding to the lever combinations associated with the various sheet sizes. Levers are prevented from actuating their associated switches when the levers are aligned with holes, and can actuate switches when they are aligned with the "flats", or closed portions of the slide-plate. The slide-plate is moved by turning a dial located on the side of the tray, which serves to push or pull the slide-plate. The printer user is required to manually set the dial for each paper size, which may be perceived as inconvenient.
The standard 250-sheet trays are equipped to automatically sense sheet size. The backstop of the tray is movable, and is mechanically linked to the slide-plate. When the backstop is moved to positions corresponding to standard sizes, the slide-plate is moved to a position exposing the proper levers, as with the optional 500-sheet tray. Although adjustment of the tray communicates differences between standard sizes automatically, the standard tray is unable to accommodate custom sizes.
Another typical adjustable tray is that associated with the Optra S2450 printer manufactured by Lexmark. The Optra S2450 operates in much the same way as the LaserJet 4000 standard tray, but also permits adjustment for some custom sizes. The Optra 2450 slide-plate has holes for standard sizes. When the backstop moves the slide-plate to a non-standard position, all levers are actuated, thus setting the switches to read a custom size. Unfortunately, the backstop and slide-plate of the Optra 2450 tray are incapable of independent adjustment. Consequently, the Optra S2450 tray cannot accommodate custom sheet sizes having the same length as standard sizes.
It can thus be seen that the need exists for a user-friendly sheet material tray that will accommodate a wide variety of standard and custom sizes.